Evaporator unit



Dec. 28, 1948. B. c. JOHNSON 2,457,561

EVAPORATOR UNIT Filed Sept. 26, 1946 4 Sheets-Sheet l Dec. 28, 1948. c. JOHNSON 2,457,561

BVAPORATOR UNIT Filed Sept. 26. 1946 I 4 Sheets-Sheet 2 fiemeo 6. Jam/sou Dec. 28, 1948. B. c. JOHNSON EVAPORA'IOR UNIT 4 Sheets-Sheet 3 Filed Sept. 26, 1946 ll 4. l II I llll l l fivrenibr 552116420 6' J/m/so/v 3. cl JOHNSON EVAPORATOR UNIT Dec. 28, 1948.

Filed Sept. 26, 1946 4 Sheets-Sheet 4 Patented Dec. 28, 1948 EVAPORATOR UNIT Bernard C. Johnson, Mundelein, Ill., assignor to Houdaille-Hershey Corporation, Detroit, Mich., a corporation of Michigan Application September 26, 1946, Serial No. 699,459

9 Claims.

1 This invention relates to improvements in heat exchangers such as evaporators and particularly relates to improvements in the circuit for the heat exchange fluid such as a refrigerant flowing therethrough.

More specifically the invention relates to an improved design of the refrigerant passages in an evaporator unit whereby maximum cooling effect from the refrigerant may be obtained and the ex hausting from the unit of unvaporized refrigerant may be minimized, if not entirely eliminated.

It has been a widely recognized fault of many evaporator units that the heat exchange load impressed upon various portions of the evaporator, particularly in the vicinity of the points where the evaporated refrigerant is withdrawn from the unit was incapable of completely vaporizing entrained droplet-s of liquid refrigerant being carried out with the vaporized refrigerant, especially during periods of rapid boiling. While a number of remedies might be evolved to offset or correct this condition. a particular merit of the present invention is that the remedy as provided herein lies not in greater complication of the evaporating unit, but rather actually in simplification of the unit, which yields a number of resultant advantages from the standpoint of manufacture, assembly, and servicing.

In accordance with the present invention two or more cooling walls, frequently having in normal use different heat exchange loads, are provided in the evaporator unit, and into a horizontal portion of one of them the liquid refrigerant is introduced and caused to flow, over an extensive path, usually a serpentine one, in heat exchange relation with that wall, after which the refrigerant is then delivered to a lower wall portion, and preferably centrally into a distributing manifold from which the refrigerant then flows through a plurality of passages in heat exchange relation with said lower wall into risers provided in end walls at opposite edges of said bottom wall, to rise into header chambers provided at the top of each set of risers in the end or side walls.

The vaporized refrigerant is then withdrawn from the upper portions of these header chambers and returned through passages in heat exchange relation with the first and upper cooling wall and caused to flow along that wall to a common outlet for the vaporized refrigerant. Thus the refrigerant from the time it enters the evaporating unit is caused to flow continuously from the inlet through the heat exchange passages provided in the first or upper wall portion, thence through the heat exchange passages in the second wall portions to the header chambers. The delivery of vaporized refrigerant gas into heat exchange relation with the first wall portion is thus given an opportunity for any entrained droplets of liquid refrigerant carried thereby to be completely vaporized by the heat load impressed upon the upper cooling wall. Hence, when the vaporized refrigerant flows through the outlet and through the return pipe to the compressor, the collection of frost due to vaporizin of liquid droplets in that return pipe can usually be eliminated or at least most satisfactorily minimized.

Accordingly, one of the objects of the invention is to provide an evaporator unit including two vertically spaced horizontal cooling Walls wherein the inlet and outlet connections for the refrigerant are provided in the upper wall portion and the refrigerant is caused to fiow in heat exchange relation first with the upper wall portion, thence through the lower wall portion from which the vaporized refrigerant is caused to return again for heat exchange relation with the upper Wall portion before it escapes to the outlet.

Another object of the invention is to provide the foregoing advantages in an evaporator unit consisting essentially of a U-shaped member having refrigerant ducts incorporated therein, the bottom of the U-shaped member being usable as a shelf and the side walls containing risers providing further refrigerating effect with another horizontal coolin wall carried by the U-shaped member and usable as a shelf or not, as may be desired.

A further object of the invention is to provide an evaporator unit of the character described having two effective cooling walls vertically spaced apart and generally horizontally extending, refrigerant ducts incorporated in both such walls, header chambers for the accumulation of evaporated refrigerants from the opposite margins of one wall and ducts for returning the vaporized refrigerant containing unvaporized droplets, if any, through one of said walls before delivery to the refrigerant outlet, to insure the further drying, as mentioned herein, of such gas in the performance of refrigerating work in that wall.

Another object of the invention is to provide a refrigerating unit of the character described in which two vertically spaced horizontal refrigerating walls are provided with refrigerant ducts formed therein and with readily connectible tubular connections providing for the fiow of liquid refrigerant through the inlet end of the duct in one wall, from the outlet end of said duct to the 3 inlet end of the ducts of the second wall, and from the outlet for vaporized refrigerant from the second Wall back again to the first wall for dryin of such gases and further refrigerating work before such gases are discharged from the unit back to the compressor.

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings, which, for the purpose of illustrating the nature of the invention and the manner of its use show two constructions embodyin g the invention.

On the drawings:

Figure 1 represents a top plan view of an evaporator made in accordance with my invention;

Figure 2 is a front elevation of the same evaporator unit;

Figure 3 is a side elevation as viewed from the left end of Figure 2;

Figure 4 is a horizontal sectional view on the line IV--IV'of Figure 3;

Figure 5 is a top plan view of a modified form of the invention;

Figure 6 is a rear elevation showing evaporator unit of Figure 5;

Figure 7 is an end elevation viewed from the right end of Figure 6;

Figure 8 is a horizontal sectional view on the line VIII-VIII of Figure 7;

Figure 9 is a partial horizontal sectional view on the line IX-IX of Figure 5;

Figure 10 is a plan view of a portion of an extruded element which may be employed as a refrigerant duct; and

Figure 11 is a plan view of the same element after portions of the side flanges have been cut away to permit bending of this duct member in the plane of the flanges, an illustration of said bending being shown in Figure 5.

In the form of the invention shown in Figures 1 to 4 inclusive, I have shown an evaporator unit, which in general consists of a top refrigerating wall I, a lower refrigeration wall 2 which may serve as a shelf, and end walls 3 and 4 both of which are also cooling or refrigerating walls.

Top wall I is composed of embossed, brazed or welded together sheets or plates including the sheets 5 and 6. Either or both of these sheets may be embossed individually or for cooperation with each other to form the necessary ducts or passages between the uppermost and lowermost surfaces of the sheets. In the present instance, as shown, the major part of the embossment is in the upper sheet 5, thereby forming a serpentine duct 1 which may be connected by any usual or suitable manner at one end to refrigerant supply pipe 8 and at its other end it may be connected in any suitable manner to a downfiow pipe 9 for conducting the refrigerant to the shelf 2. For convenience in manufacture the embossment I may be formed and subsequently the attachment to the pipes 8 and 9 may be made upon assembly of the evaporator unit.

The U-shaped structure, comprising the shelf 2 and end walls 3 and 4, is likewise formed preferably by embossing, brazing or welding together a pair of metal sheets, the upper one of which is indicated as I0 and the lower as I I.

The embossments thus formed provide a centrally positioned manifold duct I 2 extending from the front to the rear of the shelf 2, and further symmetrical embossments extending the width of the shelf connect this manifold individually with the risers such as I3 which are provided in the end walls at both ends of the shelf, these risers terminating in header chambers I4 and I5. The header chambers are then connected by means of pipes I6 and II to an embossment I8 formed in the top wall I and which in turn is connected to an outlet pipe I9 for the withdrawal of the vaporized refrigerant. Depending pockets 20 and 2| preferably are formed in the embossment I8 to provide for the accumulation of any droplets of refrigerant which have not previously been vaporized.

Rigid plates such as 22'may be riveted to the top wall I and to the'inwardly turned flanges 23 and 24 at the upper ends of the end walls in order to rigidly support the wall I upon those flanges. Usually such plates will be attached by riveting.

It may now be appreciated that the circuit for the flow of refrigerant is as follows: The liquid refrigerant is introduced through the pipe 8 and flows along the top wall I through the serpentine duct I from which it emerges into the downflow pipe 9 and thence enters the manifold I2. From the manifold the refrigerant then flows laterally to the opposite edges of the shelf 2 and enters the risers I3 and flows upwardly into the header chambers I I and I5. Preferably the liquid level will be maintained about at the midpoint of the header chambers above which will i be a vapor space from which the vaporized re-- frigerant is exhausted throughthe pipes I6 and I1 into the embossment I8, coming from both header chambers, and then is exhausted from the evaporator unit through the outlet pipe'l9. In the circuit described, refrigerant is caused to flow over an elongated path first through the top wall, thence through the bottom or shelf wall and upwardly through the side walls and as the vapor is being withdrawn from the header chambers it may, especially during rapid boiling, carry some unvaporized droplets of refrigerant. Hence, it is caused to flow through the top Wall embossment I8 before it can emerge to the outlet; thus in the embossment I8 further refrigerating effect is performed by these unvaporized droplets and the heat which such wall normally receives in the distribution of heat load in evaporator unit should normally be sufllcient to cause such droplets to vaporize. Thus the embossment I8 positioned in the rear edge of the top wall constitutes a drying duct for the spent gases.

Whereas the top wall I shown in Figures 1 to 4 inclusive constitutes the top wall of a refrigerator unit, the refrigerant circuit which has been described may also be incorporated in a unit in which the wall through which the refrigerant first flows may be positioned and employed as a shelf. Such an arrangement is shown in the form of the invention illustrated in Figures 5 to 11 inclusive, in which form I have also shown the use of extruded ducts which may be secured in appropriate heat transfer relation to the sheet metal surfaces of a refrigerator unit by welding, brazing or other appropriate means.

In this second form of the invention I provide a top shelf generally indicated as 3I and a lower wall 32 which may serve either as a shelf or as an additional cooling unit, but which is particularly adapted for use as a shelf for small packages. The ends of the bottom shelf member 32 are turned upwardly to constitute end walls 33 and 34 having header chambers35 and 36 at the upper end thereof.

The extruded duct material shown in cross section in Figure 9 is preferably first formed as indicated in the plan view in Figure 10, being first fashioned in the form of continuous strips such as 31, each strip having a duct 38 and flanges 39 and 40 of substantial width extended laterally thereof. As indicated in Figure 11, portions of these flanges subsequently may be cut off fairly close to the edge of the duct 38 at intervals such as at 4|, so indicated in Figure 11, to facilitate the bending of the duct in the plane of its flanges to form serpentines such as the serpentine 45 shown in dotted lines in Figure 5. The serpentine, thus formed, may then be welded,

brazed orotherwise secured in intimate heat conducting relation to the wall surface on which his to be mounted,

The cross sectional view in Figure 8 which is taken on the line VIII-VIII of Figure 7 indicates that the sheet'forming the'bottom shelf 32 and end walls 33 and 34 may itself be a single ex-- truded sheet having a plurality of ducts therein, connected in the usual manner to the central manifold and forming also the bottom and the of this refrigerant duct or serpentine'is connected to an inlet pipe ,46 and conducts the refrigerant through a tortuous path along the underside of the shelf 3| and then delivers this refrigerant into the downflow pipe" which delivers it to the centrally positioned manifold member 48, the passage in which is in communication with each of the ducts 49 which extend laterally of the are then evacuated. through pipe 56 for return to the compressor.

While I have shown and described two forms in which the invention may be embodied, it should be understood that the invention is susceptible of other variations and embodiments without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my invention:

1. An evaporator unit comprising a U-shaped member bent to constitute a bottom shelf and two side walls, said member having a header chamber extending along the top of each side wall, a refrigerant manifold located centrally and symmetrically of the bottom of the member, a plurality of passages extending along the bottom of said member and upwardly along the side walls providing risers in communication with the header-chambers, an upper wall supported on said U-shaped member having a serpentine refrigerantduct extending along one of its surbottom shelf and then upwardly at the end walls connected to the header chambers and 36, and

inwardly extending flanges 5| and 52 are formed 'preferably integrally with the header chambers to provide a convenient means for suspending this unit. I

At the rear end of the header chambers I pro; vide refrigerant draw-off pipes 53 and 54 both of which are connected to an extruded duct 55 which is secured upon the top of the upper shelf 3|. Thus the vaporized refrigerant and any liquid droplets contained therein are caused to flow through this drying duct 55 on the top shelf before the gases can emerge into the outlet pipe 55 for return to the compressor.

Accordingly it will be perceived that in the second form of the invention the refrigerant circuit is substantially the same as that shown on the first form. That is the liquid refrigerant is first brought into an upper wall surface, which in the second case constitutes a shelf, and flows through a serpentine duct on that surface, thence is delivered to the lower shelf through a centrally positioned manifold and flows laterally through a plurality of ducts to the opposite edges of that lower shelf and thence into the vertical risers on the side walls. The header chambers at the tops of the risers are preferably maintained in a partially flooded condition and the vaporized refrigerant is drawn off from the rear ends of these header chambers and delivered very directly into a drying duct positioned on the top shelf, thus to evaporate refrigerant droplets contained in gases, and at the same time perform directly useful refrigeration on that shelf. Said gases faces, a refrigerant inlet connected with one end of said serpentine duct, a transfer pipe connected with the other end of said serpentine duct and to said manifold for delivering refrigerant from the outflow endof the serpentine to the manifold,

a drying duct positioned along the rear .edge of said top wall, duct means connecting the vapor space in said headerzchambers with the adjoining ends of said drying duct, and a spent gas outletpipe connected with said drying duct.

2. An evaporator unit comprising a U-shaped member having a bottom horizontal wall constltuting a shelf andhaving side walls, refrigerant ducts positioned in heat conducting rela tion withsaid bottom' wall and side walls arranged to provide for symmetrical flow'of refrigerant from the middle of said bottom Wall laterally thereof and upwardly throughriser passages on the side: walls, a header chamber connected with the tops of the riser passagesin each sidewall, a refrigerant inlet adjoining'the top wall, a refrigerant duct having one end connected to said inlet and positioned in heat conducting relation with the top wall and shaped to provide for continuous flow of refrigerant in suchduct from its inlet to its outlet end, a'pipe connecting the outlet end of said top wall duct with the duct system in the bottom wall and centrally thereof, a drying duct extending along the rear edge of said top wall substantially fromend to end thereof, means connecting said drying duct with the vapor spaces in said header chambers, and an outlet for spent gases connected .with said drying duct near the middle thereof.

3. An evaporator structure comprising a first horizontal cooling wall provided with a refrigerant duct between its opposite exterior surfaces, said duct having an inlet end and an outlet end; a refrigerant inlet pipe connected with the inlet end of said duct adjoining the rear edge of said wall, a second horizontal cooling wall having a portion vertically spaced apart from the first wall and provided in said portion with a refrigerant distributing manifold incorporated between the opposite exterior surfaces of said second cooling wall portion, means connecting the outlet end of said duct centrally to said manifold for delivering refrigerant into said manifold, said second wall having formed integrally with the said manifold containing portion and at opposite edges thereof spaced apart vertical wall portions having riser ducts incorporated between the exterior surfaces thereof, said riser ducts header chamber and positioned extensively in I heat conducting relation with said first cooling wall along the rear edge portion thereof, and a refrigerant gas exhaust pipe connected for receiving said exhaust gas from said duct means.

4. An evaporator unit comprising a U-shaped member bent to constitute a bottom shelfand two side walls, said member having a header chamber extending along the top of each side wall, a refrigerant manifold located centrally and symmetrically of the bottom of the member, a plurality of passages therein extending along the bottom of said member and upwardly along the side walls providing risers in communication with the header chambers, an upper wall supported on said U-shaped member having a serpentine refrigerant duct extending along one of its surfaces, a refrigerant inlet connected adjoining the rear edge of said upper wall with one end of said serpentine duct, a transfer pipe coning the vapor space in said header chambers with the adjoining ends of said drying ducts, and a spent gas outlet pipe connected adjoining the rear edge of said upper wall with said drying duct.

5. An evaporator'unit comprising a U-shaped member providing a bottom refrigerating shelf and refrigerating side walls, refrigerant ducts on said shelf and walls arranged to provide for the flow of refrigerant from the middle of said shelf laterally thereof and upwardly along said walls, header chambers at thetops of said walls arranged to receive refrigerant from the ducts on said walls, an upper horizontal wall supported above said shelf on the walls of said member and having refrigerant passages thereon, a drying duct extending along said upper wall connected with the vapor spaces in both said chambers, a liquid refrigerant inlet connected to the passages in the upper wall, a refrigerant vapor outlet connected with the drying duct, and a transfer pipe connected to deliver refrigerant from the passages in the upper Wall to the refrigerant ducts in said shelf.

6. An evaporator unit comprising a U-shaped portions, a header chamber at the top of each side wall connected to the riser ducts therein, a horizontal upper cooling wall supported on the side walls above the bottom of said U-shaped member, refrigerant duct means on said upper wall, a drying duct on said upper wall connected to the vapor spaces in said header chambers, a refrigerant inlet connected to the duct means in said upper wall, a pipe connected with the upper wall duct means remotely from said inlet connection and with each of the laterally extending ducts in said bottom of said member, and a refrigerant vapor outlet pipe connected with said drying duct.

7. A heat exchanger comprising a U-shaped unit having fluid circulating ducts therearound terminating in header chambers in the legs of the U, a wall member spanning the space between the legs of the U and supported thereby, said wall member having first and second fluid circulating ducts, an inlet for said first duct, a conduit connecting the first duct with the fluid circulating ducts in the U-shaped unit, an outlet for the second duct, and conduit connectin the header chambers with the second duct.

8. A.heat exchanger comprising a U-shaped metal sheet, a header on the end of each leg of the sheet, ducts terminatng on said headers extending around the U and having an inlet manifold portion traversing the bight of the U, a flat sheet spanning the space between said legs and carried thereby, a drier duct traversing said sheet at one end of the U, tubes connecting the upper ends of the headers .with the ends of said drier;

duct, an exhaust tube connected to the mid-portion of said drier duct, a feeder duct extending in a serpentine path along said wall and having ends at the rear of the unit, an inlet tube connected to one end and a transfer tube joining the other end of said feeder duct with said inlet manifold.

9. An evaporator comprising a U-shaped unit having fluid circulating ducts therein terminating in header chambers in the legs of the U, a heat transfer wall member spanning the legs of the U and having a fluid circulating duct and a drying duct, a refrigerant supply tube connected to the circulating duct in said wall member, a conduit connecting the circulating duct in said wall member and the ducts in said. U-shaped unit, and conduits connecting said header chambers with the drying duct in said wall member for receiving refrigerant from the headers after the refrigerant has circulated through the fluid circulating ducts in both the wall member and U-shaped unit.

BERNARD C. JOHNSON.

No references cited. 

